A METHOD OF LOBSTER CULTURE 



From BULLETIN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908 



Proceedings of the Fourth International Fishery Congress : : Washington, 1908 




WASHINGTON :::::: GOVERNMENT PRINTING OFFICE 



1910 



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Glass SH^ Q 

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A METHOD OF LOBSTER CULTURE 



From BULLETIN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908 
Proceedings of the Fourth International Fishery Congress : : Washington, 1908 




1 



WASHINGTON :::::: GOVERNMENT PRINTING OFFICE : 



: 1910 



BUREAU OF FISHERIES DOCUMENT No. 654. 

Issued February, 1910. 



MAR s iaio 



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A METHOD OF LOBSTER CULTURE 

J- 

By A. D. Mead, Ph. D. 

Member of the Rhode Island Commission of Inland Fisheries 

& 

Paper presented before the Fourth International Fishery Congress 
held at Washington, U. S. A., September 22 to 26, 1908, and 
awarded the prize of one hundred dollars in gold offered by Hermon 
C. Bumpus for an original and practical method of lobster culture 



CONTENTS. 
j* 

Page. 

The problem . 221 

Characters and habits of larval lobsters 222 

Hatching 222 

Mode of swimming 223 

Food 1 223 

Moulting and the larval stages 223 

Difficulties in rearing 224 

Swimming habits 226 

Light reactions 227 

Parasites 227 

Food 227 

Requisites of water, etc 227 

The method 228 

Essential features and possible variations 228 

How the method meets the difficulties '_ 228 

Apparatus 229 

Hatching methods 230 

Handling the egg lobsters : 230 

Precaution as to age of fry ' 230 

Circulation current 231 

Containers for eggs and fry , 231 

Care of the fry 232 

Screens 232 

Food . 232 

Parasitic growth 233 

Results ' r 234 

Criteria of efficiency 234 

Yearly progress and output 234 

Manner of determining output 236 

Summary and interpretation 237 

Capacity and efficiency of plant 237 

Self-protective ability of fourth-stage lobsters 238 

Fifth-stage lobsters 239 

Liberation of young lobsters 239 

Evidence of increase in lobster supply 240 

Economic efficiency of the method 240 

220 



A METHOD OF LOBSTER CULTURE. 



By A. D. MEAD, Ph. D., 
Member of the Rhode Island Commission of Inland Fislieries. 



THE PROBLEM. 

Artifical breeding ought not to be content to do at its best only what nature does 
unaided. It obtains its real justification only when it is in a position to surpass nature 
in her achievements. Only thus can it accomplish the task set it — to fill up the gaps 
caused by years of excessive fishing. (Professor Ehrenbaum, in Mitteilungen des 
Deutschen Seefischereivereins, Bd. 23, Juni 1907. — Translated.) 

In the case of the lobster, nature has made adequate provision for the 
protection of the eggs up to the very time they are hatched. As is well 
known, the eggs laid in July or later in the summer or in the early fall are 
carried attached to the swimmerets under the abdomen of the female lobster, 
and there are protected until the following June or July, when they hatch out 
(figr 9, pi. xi). The young lobsters, also, when they have successfully passed 
through three moults and have attained the so-called "bottom stages" are 
equipped with structures and instincts which fit them exceedingly well for holding 
their own in the struggle for existence ; but there intervenes between the hatching 
and the attainment of the first bottom stage a brief period of two or three 
weeks in which the young lobsters, having lost utterly the protection of the 
mother animals, and not yet having acquired either the structure or the instinct 
which would give them a reasonable degree of individual security, are exposed 
and helpless to an extraordinary degree. 

Those who have studied the question of lobster culture agree that this 
short interval may properly be called the "critical period" in the lobster's 
life — the one in which occurs by far the greatest mortality. That the species 
has maintained itself without diminution (until the recent inroads by man) in 
spite of this unprotected period may be \explained by the enormous productivity 
of the individuals. A lobster of ordinary size — say 12 inches — produces at one 
time, according to Herrick, an average of about 20,000 eggs, which are so well 
protected that practically all of them hatch. This excessive productivity, how- 
ever, though a potent means of protection to the species, affords no protection 
to the individuals. 



222 » BULLETIN OF THE BUREAU OF FISHERIES. 

To one confronting the problem of lobster culture these cardinal facts in 
the natural history of the lobster point out clearly and exactly the line of attack. 
We can hardly expect to increase the number of eggs per lobster (and fortu- 
nately the number is at any rate very large) or to improve on the natural 
method of protecting and hatching the eggs, for up to the time when the eggs 
are actually hatched there seems to be little loss in nature. It is during that 
period directly after hatching, when in nature the larvae are neither protected 
from without nor equipped for self-protection, that the great opportunity offers 
to "surpass the achievements of nature" by protecting these individuals. Not 
only is this period the weak spot which artificial culture may be expected to 
strengthen^ but the superabundance of larva; normally produced for sacrifice is 
advantageous because it furnishes readily the material for cultivation. Still 
another condition particularly favors the cultivation of lobsters: It is that the 
critical period between the perfectly protected eggs and the well-equipped 
bottom-living lobster lings is so short (only two or three weeks) . Altogether, 
then, there would seem to be no doubt that the greatest practical results of 
lobster culture can be obtained by concentrating efforts upon protecting the 
fry through the critical larval period. N This has been quite generally and inde- 
pendently recognized as a fact by those who have studied the lobster problem, 
and it has been an incentive to the many attempts made by experimenters on 
both sides of the Atlantic to rear lobsters through the larval stages. It has 
been, likewise, the incentive to a continuous series of experiments and operations 
extending over exactly ten years, which have resulted in the method of lobster 
culture presented in this paper. 

CHARACTERS AND HABITS OF LARVAL LOBSTERS. 

It is a necessary preliminary to an intelligible account of the method itself 
to sketch briefly the habits of larval lobsters and to indicate some of the peculiar 
difficulties which the method has to overcome. 

Hatching. — The hatching of the ripe eggs of an individual female lobster is 
a gradual process requiring at least several days and varying with the tempera- 
ture of the water and perhaps with the lateness of the season. In the latter 
part of June, when nearly ripe lobsters are brought into the warm water of a 
shallow estuary, the hatching is accelerated. The fact of the gradual breaking 
loose of the eggs is undoubtedly of importance in the economy of the lobster 
under natural conditions, for it prevents the possibility of the swarming of the 
young fry and the attendant dangers of speedy recognition and capture. 

When the larval lobsters first break out of the egg membrane they are 
closely coiled in the form of an oval spheroid with the terminal segments of the 
abdomen bent over the rostrum. In a few moments they straighten out and 
expand and then immediately take up the pelagic life and instincts which they 
retain until they reach the so-called "fourth stage," after shedding their skins 
three times. 



A METHOD OF LOBSTER CULTURE. 223 

Mode of swimming.— The young lobsters swim by means of vibratory 
movements of their exopodite appendages, which stand out like blades from the 
thoracic legs, and the swimming is augmented by irregular jerky strokes of the 
very muscular "tail" or abdomen, which, in all the larval stages, is bent at a 
considerable angle to the cephalothorax. The swimming must be characterized 
as slow and weak when we have in mind for comparison that of most young 
fishes. At any time during the three larval stages the fry can easily be picked 
out by means of a small scoop, or even with the hand. 

In general, too, the swimming seems to be aimless in direction, so that the 
fry are easily carried along by the slightest current. This statement, however, 
though generally true, requires qualification, for under the influence of special 
stimuli the movements often become directive. The larvae respond to varying 
directions and intensities of light and, in experimental tests, to the direction of 
electrical currents. They avoid, in many cases, light-colored objects if near, 
and they are attracted by food to a rather slight degree. They will go only 
very short distances, however, after particles of food or living prey. During 
all the larval stages they exhibit practically no instinct of fear and, while they 
avoid light surfaces, they do not try to escape capture. The heliotropic and 
photopathic reactions and what may be described as the general aimlessness 
of movement are things to be reckoned with in developing a practical method 
of lobster culture. 

Food. — The natural food of the lobster must, of course, consist of pelagic 
organisms. In an examination by Dr. L-. W. Williams of the stomach contents 
of larvse in all three stages taken from the rearing bags at our station, 11 a large 
percentage were shown to have fed upon copepods and diatoms. The young 
lobsters, however, are not distinctly fastidious in this respect, and the nature 
of the stomach contents of the fry in their natural habitat would doubtless be 
found to vary according to the variety of available pelagic food. 

Moulting and the larval stages. — The instincts and behavior and the general 
appearance of the three successive larval stages are generally similar in respect to 
the features just referred to. The stages are, however, structurally well defined 
and readily recognized, there being for each a number of clearly diagnostic 
peculiarities. (See text figures p. 224 and 225.) Among the most obvious and 
easily recognizable are, for the first stage, the small size of the larvse and the 
absence of swimmerets on the under side of the abdomen; for the second stage, 
the somewhat increased size, the presence of several pairs of swimmerets and 
the absence of " tail fins " or the lateral appendages of the penultimate segment; 
for the third stage, the presence of both swimmerets and " tail fins." All stages 
have the exopodite swimming appendages and the corresponding pelagic habit ; 
none has the functional chelas or "big claws" of the adult lobster. 

According to the observations made by Doctor Hadley at our station the 
average measurements of the three successive larval stages are 8, gj4, and 11 

o Station of the Rhode Island Commission of Fisheries at Wickford, R. I., on Narragansett Bay. 



224 



BULLETIN OF THE BUREAU OF FISHERIES. 



millimeters, respectively. There is, however, a considerable range of variation 
in size, particularly in the second and third stages, and there is good evidence 
that in general the larger specimens are the better fed. For this reason the 
average size .of the lobsters of the various stages in particular rearing experi- 
ments forms, perhaps, a basis for judging whether the lobsters are doing well 
or not. 

The length of the combined larval stages varies greatly and is directly and 
powerfully influenced by the temperature and food. It ranges from nine to 




Fig. 2. — Second stage. 




Fig. 3.— Third stage. 
LARVAL LOBSTERS, LATERAL VIEW. 



more than twenty-five days (twenty -one days is extremely long at Wickford). 
From the viewpoint of practical culture, the length of the total larval period is 
of very great importance, though the duration of the first, second, and third 
stages severally does not seem to be so. 



DIFFICULTIES IN REARING. 



In artificial culture, of course, the fry must be confined in large numbers, 
and it is practically impossible to separate them from one another. Therein 
appears an initial difficulty which all experimenters have had immediately 
thrust upon them. The fry, under these circumstances, at once exhibit a most 



A METHOD OF LOBSTER CULTURE. 



225 





Fig. 4.— First stage. 



FIG. 5. — Second stage. 





Fig. 6.— Third stage. . Fig. 7.— Fourth stage. 

LARVAL LOBSTERS, DORSAL VIEW. 

B. B. F. 1908 — is 



226 BULLETIN OF THE BUREAU OF FISHERIES. 

unnatural and vicious cannibalism which Professor Morgan might well have 
added to his enumeration of characteristics impossible of development through 
natural selection and the survival of the fittest, for it can hardly be exercised 
at all under natural conditions. But whether this evil instinct arises from one 
or another biological antecedent cause or is a special inspiration in each particu- 
lar case, its reality is a constant and serious menace to lobster-culture operations. 
The cannibalistic tendencies are manifested as soon as the fry are hatched and 
continue throughout the larval period and, for that matter, even far beyond it. 
Not only do the larger and stronger specimens devour the weaker, but individ- 
uals of equal strength attack one another, and, apparently, some initial advan- 
tage determines the outcome. During the moulting period the mortality from 
these sources is naturally aggravated, because it is easy to tear to pieces the 
soft-skinned, freshly moulted individuals, while they, on their part, are unable 
to fend off attacks. 

Swimming habits. — The comparatively aimless and weak swimming habit 
which characterizes the larvae of the first three stages would seem, even in 
nature, to afford no protection, but for cultural operations, where large numbers 
of larvae are given the restricted liberty of a small arm of the sea or are more 
closely confined in cars of any sort, it contributes to one of the most exaspera- 
ting difficulties. For example, it happened that when the fry in one of the 
early experiments of this series were placed in a small cove or inlet from the 
sea, especially prepared and apparently well adapted to their requirements, 
they were carried out by the first ebbing tide, and when, subsequently, a screen 
was stretched across the gateway they were carried against it and left stranded 
high and dry. In the many attempts to confine them in various forms of cars, 
when the current was allowed to pass through to prevent stagnation, a like 
result followed — the unresisting fry were always finally borne against the sides 
or bottom. 

Once upon the bottom the larval lobsters are utterly helpless; they lie 
upon their sides or backs beating the water with their exopodite "fins" and 
"kicking" with the whole body. They can not crawl; their only salvation 
is to " kick " themselves loose from entanglement and once more rise in the water. 
When confined in considerable numbers, even in still water, they inevitably 
find their way to the bottom as a consequence of their aimless drifting mode of 
swimming. There they accumulate in corners, pockets, or eddies, and, entangled 
in debris, they fight and eat one another until, from injury or suffocation, they 
all perish. For the full appreciation of these difficulties there must be, how- 
ever, the personal recollection of particular rearing bags in which from day to 
day the precious living larvae vanished from sight, and of the quarts of bright 
pink colored dead specimens mixed with dirt and silt and remnants of unused 
food that came into view when the bag was raised for inspection. In one of the 



A METHOD OF LOBSTER CULTURE. 227 

earlier experiments 5,000 handsome first-stage larvae, appropriately designated 
from their condition the "gilt-edged lot," were placed in a new scrim bag 12 
feet square and about 4 feet deep and were carefully tended. Out of the 
number only two individuals came successfully through to the fourth stage. 

Light reactions. — As far as the movements of the larval lobsters are not 
aimless, they seem to be directed mainly by responses to light stimuli, and 
vary according to the intensity, color, and direction of rays. They also seem 
to be modified, indirectly, by background. Doctor Hadley in a study made 
at our station of the behavior of lobsters observed that the character and 
responses bore a fairly constant relation, not only to the stage, but to the period 
within the stage. In cultural operations, where cars are used, the photopathic 
responses of confined lobsters tend to bring them together into close quarters 
and are often therefore inimical because of the encouragement that this gives 
to cannibalism. In attempts to retain the fry in pounds or small estuaries, 
these responses would very likely tend to carry the lobsters to the shore, to be 
entangled in the vegetation or stranded at the ebb tide. 

Parasites. — External parasites, including stalked protozoa, fungi, diatoms, 
etc., are often a plague to the confined larvae. They grow upon the shell and 
so encumber the larvae that feeding and moving and breathing also are 
difficult or impossible. Not infrequently, in fact, the larvae are so completely 
covered with these foreign growths that they can hardly be recognized. The 
parasites are got rid of at each moult, but often they so weaken the larvae that 
moulting itself is made impossible. The danger from this source is greatest 
when, by reason of the low temperature of the water, the duration of the periods 
between moults is increased. 

Food. — Not the least of the difficulties connected with rearing lobster 
fry is the providing of proper and available food. In small experiments the 
live copepods and other pelagic food natural to the lobsters in these stages can 
be supplied, but on a large scale this is not an easy matter. Naturally, food 
that sinks to the bottom can not be reached by fry that normally swim or 
float. 

Requisites of water, etc. — The foregoing facts regarding the characteristics 
of the fry in general and the peculiarities which they manifest when in con- 
finement have to be taken into consideration in any attempt to rear the lobster 
through the critical period of its life. . To these considerations must also be 
added the important question of an adequate supply of water, uncontaminated 
by chemical or bacterial impurities, constantly furnished with the proper 
amount of oxygen, and sufficiently free from injurious gases arising from the 
metabolism of animal or bacterial content. Finally, in any method of lobster 
culture there must be taken into consideration its practicability when applied 
on a large scale and its feasibility with regard to the cost of operating. 



228 BULLETIN OF THE BUREAU OF FISHERIES. 

THE METHOD. 
ESSENTIAL FEATURES AND POSSIBLE VARIATIONS. 

A method by which lobsters can be reared through the larval stage in such 
proportions and numbers and at such a cost that it may be called a " practical " 
method has been gradually evolved at the floating laboratory of the Rhode 
Island Commission of Inland Fisheries at Wickford, R. I. (fig. i , pi. vh) . Essen- 
tially, the method consists of confining the larval lobsters in cars, either of porous 
material or provided with screen "windows," set into the ocean itself, and of 
maintaining within the cars, by mechanical means, a continuous gentle current 
of water having a rotary and upward trend. In details the method allows of 
wide variation. Good results have been obtained in small cars made out of 
water pails; in cars approximately i foot, 3 feet, 6 feet, and 10 feet in horizontal 
diameter and 1, 3, or 4 feet deep; and in either square or circular cars of cotton 
or linen scrim, of bobbinet, of canvas, or of wood. Any constant motive power 
can be used, according to the exigencies of particular cases — steam, hot-air, or 
gasoline engines; spring, weight, or water motors; or the water can be stirred 
by hand, with much labor but good results, as in our early experience. Various 
forms of power transmission may also, of course, be utilized; belt and rope 
drives over pulleys and sheaves, and steel shafting with mitered gears, worms, 
etc., have all been successfully utilized. 

HOW THE METHOD MEETS THE DIFFICULTIES. 

The way in which this very simple method overcomes the many difficulties 
of confining larval lobsters may be described in general terms as follows : In the 
first place the rearing cars are placed directly in the sea, and thereby all the 
disturbing factors so difficult to control in case of aquarium water which has 
been pumped and forced through closed pipes, stored in tanks, aerated by air 
pumps, etc., are at once avoided, and at the same time the various known and 
the subtle unknown requisites of healthy sea water are assured. The continu- 
ous upward spiral current of the contained water is the panacea of numerous 
troubles. By the upward trend of the current the larvae are kept always afloat, 
which is their normal condition and the only one to which they are by structure 
and habit adapted. The strength of the current easily overpowers their own 
weak efforts at swimming, sweeps them round and round, and effectually 
prevents their congregating in common response to the stimuli of light. 

When the fry are prevented from getting to the bottom and from congre- 
gating anywhere, several difficulties vanish. The effects of cannibalism, which 
constitute perhaps the most serious difficulty of all, are thereby greatly alle- 
viated, for the fry are to a comparatively great extent prevented from reach- 
ing one another, and of course the disastrous effects of their becoming stranded 
on the sides or lying entangled and fouled at the bottom are also obviated. 



A METHOD OF LOBSTER CULTURE. 229 

Another most important function of the current is the holding in suspension 
of solid particles of food, so that they come within easy reach of the larvae. 
Incidentally, also, it increases the supply and availability of pelagic living 
food, for the latter is drawn into the car through the bottom and kept alive by 
normal conditions of the water. An adequate supply of available food is per- 
haps the most efficacious preventive of cannibalism. 

The maintenance of normal conditions of water in a car is also accom- 
plished by this method. The temperature and density of course vary little 
from that of the surrounding water. The water is constantly renewed either 
through the porous sides or, in the case of wooden cars, through screen windows 
in the bottom, egress being allowed for by screens in the sides. Since the cur- 
rent is internal and mainly tangential to the sides of the car, the fry are not 
carried violently against the ex-current screens, as in the case of a tidal current 
passing in one side and out the other. There is not much need of rapid renewal 
of water, however, because the water is continuously brought to the surface by 
the upward trend of the current, where by exposure to the air it is recuperated 
with oxygen and relieved of waste gases due to the metabolism of contained 
animals or the decomposition of unused food. 

In a word, it may be said that by this method the pelagic lobster fry may 
be kept in confinement and under observation in inclosures of natural water, 
protected from their usual predatory enemies, maintained in natural pelagic 
condition by being prevented from going to the bottom, provided with either 
living or artificial food held in suspension, and that the tendency to cannibalism, 
always evinced when the fry are confined, can be considerably mitigated. 

APPARATUS. 

The particular form of apparatus by means of which this method has been 
successfully applied to the rearing of lobster fry during the last few years at 
Wickford is in some respects a special adaptation to the establishment in connec- 
tion with which it has been evolved, and certain details of construction are ves- 
tiges of former experiments too good to be cast aside, but not to be exactly copied 
in new construction. As it stands to-day, the apparatus consists of a house- 
boat built like a catamaran of two pontoons, with a "well" or open space 
between them, originally intended and used, indeed, for holding experimental 
cars. At both ends the space between the pontoons is decked and on each deck 
is a small house. The houseboat floats on the water, moored securely in a 
small cove directly over the channel in a good tideway (fig. 1, pi. vn). It forms 
the nucleus of a collection of skeleton rafts which nearly surround it and which 
all together occupy a considerably larger area than the houseboat itself. Four 
rafts, 19 by 75.K feet, lying two on either side of the houseboat, contain the cars 
for hatching and rearing lobster larvae. The rafts of each pair are bolted fast 
together and buoyed by barrels (fig. 1). The inside rafts on either side of 



230 BULLETIN OP THE BUREAU OF FISHERIES. 

the houseboat are fastened to the latter with eyebolts sliding over vertical rods 
to allow solely for up-and-down motion. Each of the four rafts contains six 
rearing cars, 10 by 10 feet square and 4 feet deep, so arranged that they can be held 
down in place or raised out of the water to be cleaned (fig. 4, pi. viii) . The 
rearing cars are provided with removable windows covered with 16-mesh bronze 
woven wire screens to allow for renewal of water and to prevent escape of fry. 
There are two windows about 2 feet square on the bottom and two long narrow 
ones in the middle of two opposite sides. 

For several years previous to last summer canvas bags about the dimensions 
of these boxes and provided also with screen windows were used almost exclu- 
sively. They equaled or perhaps surpassed the boxes in point of efficiency 
when they were in perfect condition, but were less durable and were more dim- 
cult to clean. 

The apparatus for keeping the water in motion consists of a two-bladed 
horizontally placed propeller of about 4 J 2 feet radius not unlike those sometimes 
in use over restaurant tables (fig. 3 and 4, pi. viii) ; the latter, in fact, suggested 
their adoption. The propeller blades are hung inside the car near the bottom and 
are made to revolve slowly — about nine revolutions per minute. The motive 
power for the propeller is furnished by a gasoline engine situated in one of the 
houses and connected with the propeller shaft by a system of steel shafting and 
mitered gears (fig. 1, 2, 3, pi. vii and viii). Each propeller can be thrown in 
and out of gear independently. 

HATCHING METHODS. 

Handling the egg lobsters. — The method now used in hatching the eggs is 
simple. The old female lobsters carrying eggs about ready to hatch (fig. 9, pi. 
xi) are put directly into boxes and the paddles are set in motion. As the old lob- 
sters crawl about on the bottom of the cars, the eggs hatch out one by one and the 
larvae, caught immediately by the upward revolving current, are carried up 
and off the bottom as they are in the ocean. Twenty to 30, or even 50 to 100, 
lobsters may be put in one car. When the number of old lobsters is large, we 
have found it well to replace the long propeller by a shorter one hung somewhat 
farther from the bottom so that the old lobsters will move freely over the bot- 
tom with tails extended and not crowd up into the corners. Screens placed 
over the top of the box, thereby shading them from the strong light, also help 
to prevent crowding (fig. 7, pi. x). As soon as a sufficient number of fry have 
hatched out the old lobsters are removed to another car to repeat the operation. 
The length of time required to hatch out a full complement of fry in one box 
varies, of course, according to the various conditions; that is, the number of egg 
lobsters, the condition of the eggs, the temperature of the water, etc. 

Precaution as to age of fry. — It is of great practical importance to have a 
full complement of fry hatch out as quickly as possible — within at least one day — 
so that all will be about the same age. 'Otherwise, when the fry moult the older 



A METHOD OF LOBSTER CULTURE. 23 1 

individuals, having passed through the moult and recovered their strength and 
appetites, are very destructive to the smaller or freshly moulted larvae. The 
effects of this discrepancy in the ages among lobsters of one batch are especially 
injurious when the older individuals reach the fourth stage, for the fourth-stage 
lobsters are endowed with strength, sagacity, directive power of movement, 
and voracity of appetite far beyond that of the other stages. When, through 
a difference in age, a number of lobsters enter the fourth stage considerably 
in advance of the others, they become veritable "sharks," as they are jocularly 
called by the attendants. On this account in the first experiments with wooden 
cars a considerable loss was sustained because certain boxes were reserved as 
hatching boxes and the fry rather than the "hens" were periodically removed 
(fig. 5, pi. ix). It being impossible to get them all out at one time, those that 
remained were often taken out together with a younger lot and later on became 
"sharks" to this brood. 

Circulation current. — For the benefit of the fry there is no doubt an optimum 
current within the car. The current can be controlled to a surprising degree 
by manipulating the propellers, although the number of revolutions per minute 
remains constant. A slight inclination to the blades makes a current very 
slow, while the maximum inclination creates a current like a mill race. The 
length of the blades, the amount of taper from base to apex, and the height 
of the blades in the water cause different effects in the character of the current ; 
for example, the relations of the rotary and the upward components of the cur- 
rent can be thus controlled and varied within wide limits. . By these and other 
variations the fry can be made to scatter evenly at all depths and distances 
from the center or to occupy various zones or strata. Experience and judg- 
ment must decide the question of optimum current at each particular phase. 
In general, it may be said that a gentle, even current made by a long, well- 
tapered blade and slight angle of inclination is usually best. 

Containers for eggs and fry. — When the rearing was done in canvas bags 
the old lobsters were confined in crates suspended in the bags, because, if let 
loose in the bottom, they were apt to tear the canvas. The crates were neces- 
sarily less spacious and had the objection of being in the way of the newly 
hatched fry, which were sometimes swept against them with considerable force 
by the current. To the other advantages of the wooden car as compared 
with the canvas bag must be added its capacity to function as a hatching pen. 
The design and construction of these wooden cars, together with many other 
recent improvements, should be credited to Mr. E. W. Barnes, the superintendent 
of the station. 

In the beginning of the experiments at Wickford the fry were transported 
from the Woods Hole hatchery by the Bureau of Fisheries, with whom we 
were in cooperation. Later experiments showed that the eggs could be stripped 
off in the usual way and placed in small rearing bags, where they would hatch. 



232 BULLETIN OF THE BUREAU OF FISHERIES. 

From these the fry were transferred to rearing cars. This method gave place 
to that of putting the ripe egg lobsters in shallow crates floated near the surface 
in the big canvas rearing bags, and then the two modifications just described 
were introduced. 

CARE OF THE FRY. 

After the fry have been hatched and transferred to the proper rearing 
car they respond well to careful treatment, and the degree of success of an 
individual experiment depends to a large degree on the care that is given. 

Screens. — Attention to the condition of the screens is worth while, for the 
intake and outflow of water can thus be regulated and, incidentally, the fine 
particles of food can be retained in the car for longer or shorter time by this 
means. The screens which we have used have been made of copper wire, bronze, 
galvanized iron, galvanized steel, scrim, and painted wire of various meshes and 
sizes of wire or thread. None is thoroughly satisfactory. They are all apt 
to clog up or to tear easily. It is to be hoped that the perforated sheet brass 
or bronze, which has been tried by Professor Gorham to his satisfaction in small 
experiments, will prove to be a great improvement. 

Food. — An appropriate and available food supply sufficient in quantity to 
fulfill the demands of healthy growth is, of course, a prime requisite in any 
fish culture, but in the case of the lobster larvae even this may not be adequate. 
Not only should the fry have food enough for their healthy growth, but they 
should never be allowed to go hungry. From hunger to cannibalism is a short 
step, and although, by means of the current, the fry are kept from congregating, 
and danger from cannibalism is, therefore, greatly lessened, there still occur 
chances of individuals coming momentarily in contact with one another, and, 
if hungry, they make the most of these opportunities. When not hungry, and 
when the cannibal instinct is not aggravated by the crowding together, they 
are fairly peaceable. 

The question of the best food for the lobster fry is still open. There are 
many kinds that the fry will eat, and fortunately by means of the stirring appa- 
ratus small pieces of almost any kind can be held suspended and therefore made 
available, but the fry have preferences, and, furthermore, the choice must involve 
the consideration of cost, the labor of preparation, waste, and the effect upon 
the water in the cars of the grease or decaying residue. 

In some of the earlier experiments several years ago the highly epicurean 
diet of lobster liver was offered, and the young larvae, innocent of its antecedents 
and, as it proved, unaware of its consequences, devoured the finely divided 
morsels ravenously. This diet did not agree with them and was discontinued 
partly on this account and partly because for operations on a large scale there 
were financial objections to its use. Shredded codfish, finely cut or ground fish 
of various kinds, clams, mussels, raw beef, beef liver, boiled beef, and many 
other foods have been tried. The fry are extravagantly fond of fresh fish, 



A METHOD OF LOBSTER CULTURE. 233 

especially the strongly flavored and oily varieties, but the pieces uneaten foul 
the car and are therefore objectionable. Clams cut out and finely chopped or 
ground have been in very general use with us. The expense, however, of 
digging and opening and the considerable waste in the larger pieces of tough 
muscle, together with the amount of decayed residue which accumulates in the 
course of two weeks during which the fry usually remain in one car, are objections 
to its continued use. 

In a careful series of food experiments at our station Doctor Emmel decided, 
after using clam, liver, beef, and some other foods, that chopped raw beef gave 
best results, all points considered. However, with a large quantity of fry to 
feed, it was found to be difficult to prepare cheap raw beef finely enough divided 
for practical use. Boiled beef coarsely ground (Hamburg steak), boiled, and 
ground again, and then beaten up in water with an egg beater, was used with 
gratifying results during the latter part of the present season. It has the 
advantage that it is easily prepared, even though the cheapest and toughest is 
chosen, and that when prepared in this way the pieces are small and corre- 
spondingly numerous. The particles are readily held in suspension, and when 
put into the water little by little with a long-handled scoop or shaken through a 
fine netting (fig. 6, pi. ix) they form a cloud of light-colored and easily visible 
particles and are distributed so evenly that they are available at every feeding 
to all the thousands of individuals in the car. Prepared in this manner, the 
beef leaves scarcely any residue; most of the uneaten finely divided pieces are 
carried out gradually through the windows. In its use one prime precaution 
must be taken; it must not be allowed to become stale or previously soaked 
with water. Care should also be taken to put the raw beef into boiling water 
and so to coagulate and conserve its albumens. 

For the reason alluded to, namely, to keep the larva? not only well fed but 
constantly satiated, thereby preventing cannibalism, it is necessary to feed them 
often, and we adopted the schedule of feeding every two hours through the 
night and day. Even with the best possible food — and this has yet to be dis- 
covered — there is a "knack" in feeding, and it is one of the points in the care of 
the fry which repays careful attention, for, besides having the advantages just 
mentioned, adequate food undoubtedly increases the rate of growth and short- 
ens the larval period. 

Parasitic growth. — The dangers from diatomaceous, fungous, and similar 
parasitic growths are especially serious when the time between moults, due to 
cold water or poor food, is relatively long. For this reason the temperature is a 
factor to be considered, when possible, in locating a hatchery. At our station 
the duration of the whole larval period is from nine to (rarely) twenty-one days, 
most of the larvse hatching in about twelve to fourteen days. We have found 
that shading the cars, as Professor Gorham recommended, seems to prevent to a 
marked degree the growth of diatoms, and also that in the wooden cars recently 



234 BULLETIN OF THE BUREAU OF FISHERIES. 

adopted the annoyance from this source is very slight when the cars are shaded. 
The insides of all of the boxes were painted, four of them white and the rest 
green. We could not see that either color had an advantage, judging from the 
output of fry. Whether the comparative immunity from diatoms of fry in 
boxes as compared with those in canvas bags was due to the painted surfaces 
of the wooden sides or to some other factor it is difficult to say. Animal growths, 
barnacles, molgulas, oysters, mussels, etc., were abundant even on the painted 
surfaces, and were scraped off each time the cars were raised. Canvas screens on 
frames (fig. 7, pi. x), set up like the sides of a roof so as to afford shade and 
to shed rain water, which occasionally comes down in such quantities as decid- 
edly to freshen the upper strata of water, are strongly to be recommended. 



CRITERIA 'OF EFFICIENCY. 

As was stated at the outset, this series of experiments and operations was 
undertaken in the conviction that the paramount problem of lobster culture was 
to raise the larvas to the fourth or lobsterling stage. It has been constantly 
borne in mind that a method of doing this to be practical must be able to pro- 
duce large quantities and without too great expense either for the cost of the 
plant or for operation. Further criteria of efficiency are, first, the proportion 
of fourth-stage lobsters to first stage, and, second, the number of "fours" to 
egg lobsters, provided, of course, that the egg lobsters on hand do not over- 
crowd the capacity of the particular plant. In placing a value upon propor- 
tions of "fourth stagers " to newly hatched fry, the number of fry dealt with in a 
single experiment has been considered; e. g., a proportion of 50 per cent carried 
through in an experiment with 500 or 1,000 fry can not fairly be compared 
with the same proportion in an experiment in which 5,000 or 20,000 fry are 
used. We have allowed ourselves also to mark our progress and the value of 
the method by comparison, first, with our former results, and, second, with the 
experiments undertaken elsewhere having the same end in view. 

YEARLY PROGRESS AND OUTPUT. 

Since this year happens to be the decennial of this particular series of 
experiments and operations, the presentation of a short summary of yearly 
results in regard to total output is appropriate. 

In 1898 Doctor Bumpus, now the honorable president of this congress, and 
at that time director of the United States Fish Commission laboratory at Woods 
Hole and member of the Rhode Island Commission of Inland Fisheries, had the 
faith and courage to undertake a new series of experiments in rearing the larval 
lobsters. Judged by the ingenuity put into them, and the experience and 
encouragement got out of them, these experiments during the first year were 



A METHOD OF LOBSTER CULTURE. 235 

successful, though the number of fry reared was small. The total output is sum- 
marized in the report of the work in these words : 

Several lobsters were actually raised to the stage when the characters of the adult 
are assumed — the fourth moult." 

The next year, 1899, the results were better because of the use of "a large 
bag of scrim made after the fashion of a fish pocket and hanging down into the 
water from a square floating frame." The output is given in the following 
words : 

By the methods above described, and after many failures, accidents, and reverses, 
we succeeded in raising several hundred lobsters to the fourth stage. 

During the following season, 1900, several lots of newly hatched fry were 
transported from the United States Fish Commission station at Woods Hole to the 
new floating laboratory of the Rhode Island Commission of Inland Fisheries at 
Wickford, R. I. (the two commissions working in cooperation), where further 
experiments with scrim bags were started parallel to those still being conducted at 
Woods Hole. At the floating laboratory at Wickford the trials and reverses of 
the previous year at Woods Hole were again experienced, but the experiments 
were under the eye of the person in charge, by night as well as by day, because 
the small houseboat functioned as a residence. The greatest virtue of the 
loosely hung scrim bags consisted in the undulatory "peristaltic" movements, 
due to wind and tide, which tended to keep the lobsters off the bottom, but it 
was observed that during the nights there were periods of dead calm and of 
slack tide, when the fry sank to the bottom and died. This led to the simple 
conclusion that if the fry, left to themselves, persisted in sinking to the bottom 
to die they must be stirred up and prevented from sinking; so after this they 
were stirred with an oar continually night and day. The total reared to the 
fourth stage was 3,425. The results showed unequivocally that the proper 
principle had been discovered, and immediately plans were laid to substitute a 
mechanical apparatus by which this method could be less laboriously carried 
into effect. Curiously enough, some large two-bladed fans revolving over a 
restaurant table for the purpose of driving away flies suggested the type of appa- 
ratus suited to the purpose, and this type has been in use ever since. 

The next year, 1901, the United States Bureau of Fisheries again cooperated 
with the Rhode Island commission. Some of the fry were imported from Woods 
Hole and some were hatched at Wickford. An apparatus for using the two- 
bladed propeller was designed and installed by Mr. G. H. Sherwood. The 
results confirmed the correctness of the principle, and the output for the year 
was 8,974. 

During the subsequent years the method has been developed and the appa- 
ratus again and again remodeled to incorporate the results of our failures and 

o Bum pus, Twenty-ninth Annual Report of the Rhode Island Commissioners of Inland Fisheries, 
1898, p. 98. 



236 BULLETIN OF THE BUREAU OF FISHERIES. 

successes and in the effort to obtain results on a scale large enough and with cost 
small enough to deserve the adjective "practical." The total outputs for the 
years are: 

1906 C189, 384 

1907 ^294,896 

1908 £322,672 



1898 (a) 

1899 (6) 

1900 3,425 

1901 8,974 



1902 27,300 

1903 13,500 

1904 50,597 

1905 103,572 



The rearing of considerably over 300,000 lobsters in the small plant at 
Wickford recalls the confession of faith written ten years ago, at the conclu- 
sion of the first season's work : 

We know perfectly well that many others have failed in doing what we attempt, 
but until we are thoroughly convinced that the young lobster can not be "brooded" 
we propose to continue our work/ 

Manner of determining output. — It was early realized that "estimates" 
of the number of lobsters in experimental work are practically worthless and 
therefore all the fourth-stage lobsters which are taken account of at all (many 
thousands of others have accidentally escaped) have been individually counted. 
Within the last few years, when the numbers have run up into hundreds of 
thousands, the operation of counting individuals has consumed much time, but 
the satisfaction of accuracy in results has been sufficient compensation. A 
comparatively easy and very accurate method of counting is now in use. The 
" lobsterlings " are dipped out of the hatching boxes with flat woven- wire strainers 
which take up from one to twenty at a sweep; these are recorded on an auto- 
matic counting register held in the hand. The count at each sitting is then 
posted (fig. 7 pi. x). 

It is of little use to estimate the number of a lot of first-stage fry. More 
than once the lots so estimated, even by experts, have yielded not more than 
10 per cent of the estimated number; sometimes, no doubt, they would run 
considerably over. For this reason, in order to ascertain the proportion of 
newly hatched fry to the fourth stage, the individuals must be counted both 
before and after the experiment. This is a rather tedious process, but it is war- 
ranted and necessary when new methods or new devices of construction are 
tested for their relative efficiency. 

Tested by this method both the large canvas bags used until this year and 
the present boxes have yielded on several tests 40 per cent of fourth-stage lob- 
sters from lots of 20,000 newly hatched fry. In one test of the canvas bags 48.2 
per cent were obtained in a 20,000 lot. In testing for relative value of foods in 

"Several." c 24,800 to fifth stage. e 5,481 to fifth stage. 

b "Several hundred." d 4,900 to fifth stage. / Bumpus, op. cit. 



A METHOD OF LOBSTER CULTURE. 237 

1907, 40.6 per cent and 39 per cent were obtained in two respective tests, while 
one of the boxes yielded 42 per cent. About 40 per cent may be considered a 
fair yield for lots of 20,000 under the present system of operation. By using 
more fry more fourth-stage lobsters can be obtained from a single car, but 
the percentage probably falls. 

There is another very different point of view from which the efficiency 
of the present method may be judged, namely, the number of fourth-stage 
lobsters which it will produce per egg lobster under fair conditions. Toward 
the latter part of the season two years ago, when the supply of eggs from the 
ordinary source had suddenly been cut off, 56 egg lobsters were received from 
Noank through the courtesy of the Connecticut Fish and Game Commission. 
From these there were hatched and reared to the fourth stage 84,896 young 
lobsters, giving an average of somewhat over 1 ,500 per egg lobster. 

SUMMARY AND INTERPRETATION. 

Summarizing the actually obtained results of rearing lobster fry to the 
fourth stage by the method herein described: Since the present method was 
first put into operation in its crude form where the water was stirred by an 
oar the output has each year (with one exception) increased. The extremes 
are represented by the total of 3,425 in 1900 and of 322,672 in 1908. The 
grand total for the eight years is 1,014,320, more than half of which were pro- 
duced in the last two years. With lots of 20,000 newly hatched fry from 40 
to 48 per cent (counted) have been carried through to the fourth stage fre- 
quently, and 40 per cent may be said to be a fair average to expect under good 
conditions. From 56 egg lobsters nearly 85,000 fourth-stage lobsters were 
obtained, showing an average of about 1,500 per individual. 

In order to interpret these results fairly, there are certain things which 
deserve consideration. Even when operating on a practical scale, we have 
been feeling our way over new ground to further improvement of the method. 
Not a year has passed without decided changes in the method or the apparatus. 
While this procedure leads to the best final outcome, it does so at a sacrifice 
of immediate results. Accidents, also, of certain classes — for example, the 
loss of larvae through broken screens — must be charged against the present 
apparatus and not against the method. Delays in construction, difficulty in 
getting egg lobsters, etc., may be due to misfortune or to mismanagement, but 
do not affect the permanent value of the method. 

Capacity and efficiency of plant. — The plant as it stands to-day must be 
judged by the results actually attained ; but having watched closely its operation 
I may venture the personal opinion that it has not yet produced to its full 
capacity and that the 24 cars are capable, under good conditions and with allow- 
ances for inevitable mistakes, of hatching and rearing 500,000 lobsters in the 



2 3 8 



BULLETIN OF THE BUREAU OF FISHERIES. 



six or eight weeks which constitute an average season. This is a conservative 
estimate based on the following deductions: If all the 24 cars were filled three 
times, allowing two weeks for passing through the moults, with an average 
output per car of 10,000 each time (which is considerably below frequent actual 
production), the total output would be 720,000. With a constant supply of 
fry sufficient to fill the plant to its full capacity throughout the season, this 
estimate could probably be raised. 

As has been stated before, many features of the present installation are 
to be considered as vestigial structures and others as designed for one function 
and adapted to another in the course of the evolution of the plant. A new plant, 
therefore, built to operate the same rearing cars would be different in many 
details. The cost of a plant capable of duplicating the work of the one at 
Wickford has been calculated by Mr. E. W. Barnes, superintendent of the Wick- 
ford plant, at approximately $2,000, specified as follows: 

Cost of a Rearing Plant Consisting of 24 Rearing Boxes Capable of Turning out over 500,000 
lobsterlings in a season. 



2 yi horsepower engine $200 

Houseboat 300 

Four rafts 350 

Gearing 400 



24 boxes 

Miscellaneous supplies. 



Total 1,800 



The above items have been figured economically but quite liberally, and in localities where materials 
can be readily secured the cost might be considerably lessened. The actual cost of rearing lobsters 
to the fourth stage is a little less than $3 per 1,000. This includes labor, food, gasoline, and in fact 
all necessary running expenses, but does not include the cost of egg lobsters. 

This amount would, of course, vary with the time and place where the 
plant was constructed and also with the kind of materials used. 

Self-protective ability of fourth-stage lobsters. — An acquaintance with thou- 
sands of fourth-stage lobsters from personal observation and through the spe- 
cial scientific studies of members of our staff increases even our former estimate 
of their superiority over the larval lobsters. Immediately after arriving at this 
stage they are able to crawl over the bottom, to burrow and hide, to fight, and 
to forage in most striking contrast to the larval lobsters in any stage of devel- 
opment. In the first few days of the fourth stage the lobsterlings are good 
swimmers — this is their "redeeming vice" — but the swimming is strong and 
bears no comparison to the aimless drifting movement characteristic of larval 
stages. The lobsterlings dart hither and thither in pursuit of food, and for the 
first time they show a decided fear and strive to avoid capture. When left in 
the rearing cars, which have a strong internal current of water, thousands of 
these lobsters are often seen all swimming mightily in one direction against the 
strong current for hours at a time; but these same lobsters when taken out of 
the car and put into another one provided with sand and gravel will often take 
immediately to the bottom and behave as if they had always lived in this habitat. 



A METHOD OF LOBSTER CULTURE. 239 

It is an interesting and important fact that the tendency to swim decreases 
rapidly during their sojourn in the fourth stage and also that they can be encour- 
aged to live on the bottom by being brought into contact with it. These facts 
have suggested two modifications in the usual procedure in liberating lobsters — 
first, that of holding the lobsterlings in special rearing cars for a few days after 
they reach this stage, keeping up the current in order to keep the lobsters sepa- 
rated and to keep their food in suspension, and, second, that of liberating them 
in such a manner that they will immediately touch the bottom, in which case 
they are not so apt to make swimming excursions through the water. An ingen- 
ious device for the latter purpose has been invented by Mr. Barnes. The young 
lobsters are sunk in barrels which have the numerous holes for their exit so cov- 
ered up that while the lobster can get out predacious fishes can not get in. 

It is comparatively easy to care for fourth-stage lobsters. Space and plenty 
of food are about the only requisites. Like the fry, they are cannibals in pro- 
portion as they are hungry and crowded together; but unlike the fry, they con- 
trol their own movements and go where they please, whether swimming, or 
crawling, or burrowing, and they have, moreover, a strong instinct of self- 
preservation. 

Fifth-stage lobsters. — There is much to be said in favor of rearing lobsters 
to the fifth stage before liberating them, and this is not difficult to do, but requires 
space. In some experiments conducted without great care 80 per cent were car- 
ried from the fourth to the fifth stage in large lots of several thousand. In addi- 
tion to the advantage in the matter of size, strength, and bottom-loving instinct, 
which favors the fifth-stage lobsters, an additional advantage lies in the fact 
that the duration of the fourth stage can be shortened by abundant feeding. 
Doctor Emmel showed in a most convincing manner that by feeding alone, all 
other conditions being identical, the duration of this moult can be varied from an 
average of eleven to an average of twenty -four days. 

Liberation of young lobsters. — Every visitor at the rearing plant asks the 
embarrassing question, "What proportion of the liberated lobsters live to grow 
up?" Only once was a definite and satisfactory answer given to this question 
and that by a new recruit on his first day's duty. 

In 1 90 1 when the experiments began to indicate that a large number of 
lobsterlings could most likely be liberated from our establishment, investiga- 
tions were started to find out whether the physical conditions of the waters of 
Narragansett Bay were such that the young lobsters could live here throughout 
the year. Of this there is now no doubt, for the specimens reared from the egg 
have year after year been kept over winter in cars sunk or floated in the harbor 
at Wickford. Several were kept for three successive years and finally were 
lost through accident. 



240 BULLETIN OF THE BUREAU OF FISHERIES. 

EVIDENCE OF INCREASE IN LOBSTER SUPPLY. 

The young lobsters have been liberated mainly in the upper half of Narra- 
gansett Bay, because for many years previous to our operations small lobsters 
have been conspicuously absent from these precincts, according to the statements 
of fishermen. Within the last three or four years a great many reports have 
come in of small lobsters from an inch to 4 or 5 inches in length being caught in 
the lobster pots and escaping through the slats when the pots were drawn up; 
also of small lobsters up to 8 inches in length dug out of the mud in the early 
spring by the clam diggers. These reports have been numerous and are increas- 
ing and apply to those particular districts in the upper part of the bay in which 
our lobsters have been liberated. They have occasioned remarks of surprise 
by the fishermen, because this region has been so long barren of small lobsters. 
Whether this can be taken as good evidence of the effect of liberating in these 
waters about half a million of young lobsters reared to the bottom stage (the 
number up to two years ago) is at present of course entirely a matter of opinion. 

ECONOMIC EFFICIENCY OF THE METHOD. 

At the end of an account of the method of rearing lobsters and of the 
results actually attained, a brief speculation with regard to the efficiency of the 
method from the economic standpoint may be permissible. 

It is often true in biology that one can draw conclusions as to causes and 
effects from observation and comparison of normal occurrences. In the breed- 
ing of animals we seem to have a case in point. Fishes which produce many 
thousands of eggs at a time, but whose young are left almost utterly unpro- 
tected, often do not maintain so great a numerical abundance as do other 
species (like the dogfish) , which produce only a very few individuals at a time, 
but give the young a high degree of protection. 

While the relative values of the larval and fourth-stage lobsters can not, 
for a long time at any rate, be determined accurately by direct experiment, it 
would seem that a comparison of the breeding habits of the lobster and the 
crayfish would, as Ehrenbaum has pointed out, furnish data for a tentative 
valuation. Where the lobster produces .at one time 20,000 fry (Herrick got 
an average of 21,351 eggs from 414 observations of 12-inch lobsters), the cray- 
fish produces approximately 100 young (Ehrenbaum), which it protects to a 
stage comparable with the fourth-stage lobster. Assuming, then, that the 
100 young fourth-stage lobsters and the 20,000 newly hatched lobster fry are 
of equal value for maintaining the species, the ratio of individual values would 
be 200 : 1. Our method of artificial culture is capable of obtaining 8,000 fourth- 
stage lobsters from 20,000 fry. It is able, therefore, by taking advantage of 
the lobster's great productivity, to obtain 80 times as many young of this 
particular advanced stage as are necessary for the maintenance of the species 
under natural conditions. 



But. U. S. B. F., 1908. 



Plate VII. 




Fig. 1. — General \ 
pontoons show at 
seen in the right-hand floats. 




Fig. 2. — Inside of box toward one corner. 1, Sleeve coupling for disjointing 
propeller shaft ; 2 , lever for throwing shaft out of gear ; 3 , train of mitered 
gears reducing speed of propeller shaft; 4, type of adjustable hangers in 
general use ; 5, inside corner of box. 



Bui,. U. S. B. F., 1908. 



PLATE VIII. 




g forward and toward house boat. The appearance of 
of the propeller shafts are shown in the nearest car. 




Fig. 4. — One of the outside floats, car raised. The size and shape of the propeller is well shown. 



Bul. U. S. B. F., 19c 



Pl,ATR IX. 





Bui,. U. S. B. F., 1908. 



Pl.ATK X. 




Fig. 7. — Method of counting fourth-stage lobsters. The awning is laid 
The lobsters are caught up in the woven-wire dipper and shaken off into ; 
bucket of water. In the left hand is held the automatic counter. 




Fig. 8.— Improved towing car designed by Mr. Ban 
are towed in this car, and fishes of various kinds have 
most excellent results. 



Bnu U. S. B. F., 1908. 



Plate XI. 




Fig. 9. — Lobster with eggs. 



f^ 



Pt3^ 



LIBRARY OF CONGRESS 

mi 



